When eating foods or taking beverages, we feel various tastes among which are included tastes felt as unfavorable tastes. Bitterness, astringency, harsh taste, and the like are generally received as unfavorable tastes in many cases. Sourness is in some cases received as a favorable taste, but sourness with tongue-biting stimulus is received as an odd taste and is not acceptable for us. An attempt to suppress or reduce these unfavorable tastes has conventionally been made. Further, to the contrary, an attempt to enhance a juice-like feel or a volume feeling of foods and beverages, which are considered as favorable tastes, has been made as well.
As a method for improving the flavor of such foods and beverages, various methods such as methods of using fruits, fruit juices, squeezes or ingredients of fruits or fruit juices have also been known. As some of these methods, there are illustrated, for example, a method of reducing sourness or bitterness of foods by using a cranberry juice concentrate which has been subjected to decolorizing treatment and electrodialyzing treatment (see Patent Document 1), a method of giving a more natural body, a richness, and a thickness to foods and beverages by using vicenin-2 as an active ingredient (see Patent Document 2), a method of improving flavor of protein foods by adding an extract of grape seeds or grape skins (see Patent Document 3), a method of reducing various unfavorable smells and tastes of foods and beverages and improving flavor thereof by adding a hesperidin glycoside or a mixture of hesperidin glycoside and hesperidin (see Patent Document 4), a method of masking an astringent taste or a saltiness by compounding a berry in an oral composition containing hydroxycitric acid (see Patent Document 5), and a method of enhancing a richness, juiciness, body, and mildness to a taste of foods and beverages or of a composition for oral cavity by adding a high-boiling point fraction obtained in a dewaxing treatment of a citrus cold press oil (see Patent Document 6).
However, with the method of using a cranberry fruit juice concentrate described above, the process for preparing the raw material is so complicated that the method involves a problem in view of production cost. Also, with the method of using vicenin-2 as an active ingredient, an extent of the flavor-improving effect is limited, and a wider extent of the flavor-improving effect is demanded. Further, with the method of using an extract of grape seeds or grape skins, its application is limited to improvement of flavor of protein foods, thus the method involving a problem that its application is limited. The method of using a hesperidin glycoside or a mixture of hesperidin glycoside and hesperidin involves a problem that its flavor-improving effect is insufficient. The method of compounding a berry described above involves a problem that kinds of flavor to be improved are limited. The method of using a high-boiling point fraction obtained in a dewaxing treatment of a citrus cold press oil involves a problem that, since the flavor improving agent is an oil-soluble material, its application is limited.
As mentioned above, various methods for improving flavor of foods by using fruits, fruit juices, fruit juice ingredients, and the like have been conventionally known. However, these methods involve such problem as that foods to be used are limited, that the production process is complicated, or that the flavor-improving effect is insufficient. A flavor improving agent, therefore, is demanded which can exhibit its effects even when added to foods in only a small amount, which gives almost no taste or smell, which has a high safety, which can be produced at a low cost, and which can be widely used with respect to kinds of foods and beverages to be applicable and kinds of flavors to be improved. Such improvement of flavor is not limited only to foods and beverages but is required with pharmaceutical products to be used as oral compositions, oral care products, and the like as well. Also, by incorporating a flavor improving agent in a flavor composition which is used for these various products, flavor-improving effects can be given to the various products together with favorable aroma.
Additionally, it has been conventionally known to remove unpleasant smells liable to generate during storage of fruit juices by using a nonionic porous polymer resin (see Patent Document 7). However, it have not been confirmed that fruit juice components adsorbed on the resin have flavor-improving effects. It has also been known to produce a natural flavor by adsorbing aroma ingredients of fruit juice on a porous polymer resin and recovering it (see Patent Document 8). However, since its object is to recover an aroma, it is impossible to conduct removal of a solvent by distillation or conduct a heating, which cause lost of low-boiling point ingredients and thermal change of aroma.